Wanyi reservoir

Wanyi reservoir

Located in Sai Kung District, Hong Kong, high island reservoir is the largest reservoir in Hong Kong, with a capacity of 60 billion gallons, equivalent to about 273 million cubic meters. The project of Wanyi reservoir is planned to start in 1969, start in 1971 and be completed at the end of November 1978. It is the last reservoir built in Hong Kong. Together with the second largest reservoir in Hong Kong, chuanwan fresh water lake, it has accounted for 87.2% of the total storage of 586 million cubic meters in Hong Kong.

Wanyi reservoir is the most expensive public works project in Hong Kong in the 1970s. When it was completed in 1978, it cost HK $1.35 billion. For the first time, the government changed the division of the local administrative region in response to the needs of public works projects. It divided the South Yorkshire government of the new territories into the Richmond government of Sai Kung and the Richmond government of outlying islands. This has become the most extensive country park in Hong Kong.

brief introduction

Wanyi reservoir is the most expensive public works project in Hong Kong in the 1970s. When it was completed in 1978, it cost HK $1.35 billion. For the first time, the government changed the division of the local administrative region in response to the needs of public works projects. It split the South Yorkshire government of the new territories into the Sai Kung and Outlying Islands Government. It has also become the most extensive country park in Hong Kong. Many villages, including lanniwan village, were inundated during the construction.

The original site of the reservoir is Guanmen waterway, which belongs to the same reservoir built in the sea as chuanwan freshwater lake. The project involves the construction of two main dikes at both ends of the Guanmen waterway to connect the mainland of Sai Kung with the third largest island of Hong Kong, Liang Chuan Wan Chau. The two dams are 64 meters high and there are three auxiliary dams.

Wanyi reservoir is composed of two dams, east dam and west dam. The dam closed both ends of the Strait, forming a huge reservoir, the project is quite large. The overall building heights of Dongba and Xiba are 104 meters and 90 meters respectively. Dongba was completed in 1978. At that time, it was the highest rock fill dam in the world. The downstream of the dam faces the Pacific Ocean. In order to prevent the turbulent sea waves and consolidate the building structure, engineers built an additional breakwater composed of 7000 anchor stones, which is unique.

The huge anchor shaped breakwater of the east dam of Wanyi reservoir has its own characteristics. It has a unique taste to watch the sunrise on the dam facing the humid sea breeze. Dongba and pobianzhou areas are surrounded by strange hexagonal columnar tuff with extraordinary momentum. Live along the second section of MacLehose path and pass Langjia Bay. The beach here is very beautiful, like a paradise. The water is clear, the sand is young, and the bottom is clear!

The most interesting and special thing about Wanyi reservoir is the origin of its name. There was a village at the bottom of Wanyi reservoir, named Wanyi village! Because of the construction of the reservoir to commemorate the inundation of Wanyi village, the reservoir was named Wanyi reservoir. Hong Kong is an extremely efficient city, too high to allow any buildings to fall in place and then decay. Unexpectedly, a village with a history of more than 100 years has been preserved under the Wanyi reservoir.

Wanyi reservoir won the fourth place in the "top ten scenic spots of Hong Kong" held by friends of country parks of Hong Kong, Lions International Hong Kong Macao 303 district and agriculture, fisheries and Conservation Department.

Construction background

Many large reservoirs were built in Hong Kong from the 1950s to the 1970s. However, due to the population explosion, the reservoirs are still inadequate. Since then, the construction of the chuanwan freshwater lake in Hong Kong has not been able to cope with the growing demand for fresh water despite its huge capacity. After the serious water shortage from 1963 to 1964, water supply was needed every four days, and the project of Wanyi reservoir was started.

The reservoir is located in the narrow seaway between the South Bank of Saigon Peninsula and liangchuanwan island. Engineers built two additional dikes in Guanmen Strait at the East and West ends of the Seaway, and then pumped out the sea water to inject fresh water to make it a freshwater lake.

The initial cost of this huge project is estimated to be HK $750 million, 150 million more than that of chuanwan freshwater lake, with a storage capacity of 50 to 75 billion gallons. In 1969, the Hong Kong government began to draft a plan. In 1971, it officially started construction and was completed at the end of November 1978. It took seven years. The total investment far exceeded the original budget, with a cost of HK $1.35 billion and a reservoir capacity of 60 billion gallons, increasing the storage capacity of Hong Kong to 586 million cubic meters (128.92 billion gallons).

engineering

The whole Wanyi reservoir was built on the Precambrian igneous rhyolite terrain. To build the Wanyi reservoir in the great sea, the engineers finally decided to build two main dams in the East and West. Facing the South China Sea, Dongba is 1593 feet long and 348 feet high; facing Niuwei sea and liangchuanwan sea, Xiba is 2470 feet long and 333 feet high. The project is extremely complicated. In order to resist the sea wave erosion, each of the East and West Main dams is built in the form of main and auxiliary dams. The main dam is used to store fresh water, and the auxiliary dam (weak wave dike) is used to resist the sea wave erosion. The main dam and the auxiliary dam are separated by buffer zone. Dongba is famous for its huge and complicated concrete breakwater. Dongba breakwater is composed of more than 2500 double T-shaped precast concrete members, directly facing the open sea. Because the west dam is located in the inner bay, the erosion is far less than that of the east dam, so the concrete breakwater is not set up, and only rhyolite rock blocks are piled up as the auxiliary breakwater.

Before the construction of the main dam, first of all, the cofferdam should be built at the place where the dam is built to separate the sea water, drain the sea water within the sea bed, and dig out the clay and sand before the dam is built, so that the main dam can be firmly built on the hard rock. In addition to the main dam, there are three smaller auxiliary dams in liangchuanwanzhou and Saigon Peninsula to close the adjacent valleys and prevent the reservoir from overflowing.

The water supply network of the Wanyi reservoir consists of a number of water supply tunnels with a diameter of 10 to 13 feet and a total length of about 25 miles. The main line of the tunnel is 74000 feet (14 miles), which flows from the North pool of the Wanyi reservoir, across the whole Saigon Peninsula, through Dahuan village of Saigon to Shatin water treatment plant.

In addition, a total of 26000 feet (5 miles) of tunnel system with six branches, including beitanao tunnel and Xiwan tunnel, mainly collects water from low-lying rivers and streams. All water tunnels were completed in 1975. The storage of chuanwan fresh water lake can also be diverted to Wanyi reservoir through the water conveyance system. The distribution of the water pipe network is very close, and it can be used to transfer water with the storage of chuanwan fresh water lake, which makes the allocation of fresh water resources in Hong Kong more flexible.

Wanyi reservoir covers an area of 2000 mu, only three-quarters of chuanwan freshwater lake, but its dam is relatively high, so its capacity is about 22% more than that of freshwater lake. In the whole construction process, a total of five engineers and construction workers were killed.

refugee camp

In Hong Kong, in the 1980s, the British Hong Kong government faced with the Vietnamese boat people problem in Hong Kong and built the Wanyi detention center in Xiba, Wanyi reservoir. The center was closed on May 26, 1998, and now the site is a grassland. The grassland can be used as a site for Chuang Hing Water Sports Centre and will also be lent to the Hong Kong Scouts Association for large-scale camping activities. This includes the world synchronous camp to celebrate the centenary of scouts from July 29 to August 3, 2007.

Address: Sai Kung, Hong Kong

Longitude: 114.35498809814

Latitude: 22.376039505005

Chinese PinYin : Wan Yi Shui Ku